/*
 * Copyright 2002-2009 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.util;

import java.lang.reflect.Array;
import java.util.Arrays;

/**
 * Miscellaneous object utility methods.
 *
 * <p>Mainly for internal use within the framework; consider
 * <a href="http://jakarta.apache.org/commons/lang/">Jakarta's Commons Lang</a>
 * for a more comprehensive suite of object utilities.
 *
 * <p>Thanks to Alex Ruiz for contributing several enhancements to this class!
 *
 * @author Juergen Hoeller
 * @author Keith Donald
 * @author Rod Johnson
 * @author Rob Harrop
 * @since 19.03.2004
 * @see org.apache.commons.lang.ObjectUtils
 */
public abstract class ObjectUtils {

   private static final int INITIAL_HASH = 7;
   private static final int MULTIPLIER = 31;

   private static final String EMPTY_STRING = "";
   private static final String NULL_STRING = "null";
   private static final String ARRAY_START = "{";
   private static final String ARRAY_END = "}";
   private static final String EMPTY_ARRAY = ARRAY_START + ARRAY_END;
   private static final String ARRAY_ELEMENT_SEPARATOR = ", ";


   /**
    * Return whether the given throwable is a checked exception:
    * that is, neither a RuntimeException nor an Error.
    * @param ex the throwable to check
    * @return whether the throwable is a checked exception
    * @see java.lang.Exception
    * @see java.lang.RuntimeException
    * @see java.lang.Error
    */
   public static boolean isCheckedException(Throwable ex) {
      return !(ex instanceof RuntimeException || ex instanceof Error);
   }

   /**
    * Check whether the given exception is compatible with the exceptions
    * declared in a throws clause.
    * @param ex the exception to checked
    * @param declaredExceptions the exceptions declared in the throws clause
    * @return whether the given exception is compatible
    */
   public static boolean isCompatibleWithThrowsClause(Throwable ex, Class[] declaredExceptions) {
      if (!isCheckedException(ex)) {
         return true;
      }
      if (declaredExceptions != null) {
         int i = 0;
         while (i < declaredExceptions.length) {
            if (declaredExceptions[i].isAssignableFrom(ex.getClass())) {
               return true;
            }
            i++;
         }
      }
      return false;
   }

   /**
    * Determine whether the given object is an array:
    * either an Object array or a primitive array.
    * @param obj the object to check
    */
   public static boolean isArray(Object obj) {
      return (obj != null && obj.getClass().isArray());
   }

   /**
    * Determine whether the given array is empty:
    * i.e. <code>null</code> or of zero length.
    * @param array the array to check
    */
   public static boolean isEmpty(Object[] array) {
      return (array == null || array.length == 0);
   }

   /**
    * Check whether the given array contains the given element.
    * @param array the array to check (may be <code>null</code>,
    * in which case the return value will always be <code>false</code>)
    * @param element the element to check for
    * @return whether the element has been found in the given array
    */
   public static boolean containsElement(Object[] array, Object element) {
      if (array == null) {
         return false;
      }
      for (Object arrayEle : array) {
         if (nullSafeEquals(arrayEle, element)) {
            return true;
         }
      }
      return false;
   }

   /**
    * Append the given Object to the given array, returning a new array
    * consisting of the input array contents plus the given Object.
    * @param array the array to append to (can be <code>null</code>)
    * @param obj the Object to append
    * @return the new array (of the same component type; never <code>null</code>)
    */
   public static Object[] addObjectToArray(Object[] array, Object obj) {
      Class compType = Object.class;
      if (array != null) {
         compType = array.getClass().getComponentType();
      }
      else if (obj != null) {
         compType = obj.getClass();
      }
      int newArrLength = (array != null ? array.length + 1 : 1);
      Object[] newArr = (Object[]) Array.newInstance(compType, newArrLength);
      if (array != null) {
         System.arraycopy(array, 0, newArr, 0, array.length);
      }
      newArr[newArr.length - 1] = obj;
      return newArr;
   }

   /**
    * Convert the given array (which may be a primitive array) to an
    * object array (if necessary of primitive wrapper objects).
    * <p>A <code>null</code> source value will be converted to an
    * empty Object array.
    * @param source the (potentially primitive) array
    * @return the corresponding object array (never <code>null</code>)
    * @throws IllegalArgumentException if the parameter is not an array
    */
   public static Object[] toObjectArray(Object source) {
      if (source instanceof Object[]) {
         return (Object[]) source;
      }
      if (source == null) {
         return new Object[0];
      }
      if (!source.getClass().isArray()) {
         throw new IllegalArgumentException("Source is not an array: " + source);
      }
      int length = Array.getLength(source);
      if (length == 0) {
         return new Object[0];
      }
      Class wrapperType = Array.get(source, 0).getClass();
      Object[] newArray = (Object[]) Array.newInstance(wrapperType, length);
      for (int i = 0; i < length; i++) {
         newArray[i] = Array.get(source, i);
      }
      return newArray;
   }


   //---------------------------------------------------------------------
   // Convenience methods for content-based equality/hash-code handling
   //---------------------------------------------------------------------

   /**
    * Determine if the given objects are equal, returning <code>true</code>
    * if both are <code>null</code> or <code>false</code> if only one is
    * <code>null</code>.
    * <p>Compares arrays with <code>Arrays.equals</code>, performing an equality
    * check based on the array elements rather than the array reference.
    * @param o1 first Object to compare
    * @param o2 second Object to compare
    * @return whether the given objects are equal
    * @see java.util.Arrays#equals
    */
   public static boolean nullSafeEquals(Object o1, Object o2) {
      if (o1 == o2) {
         return true;
      }
      if (o1 == null || o2 == null) {
         return false;
      }
      if (o1.equals(o2)) {
         return true;
      }
      if (o1.getClass().isArray() && o2.getClass().isArray()) {
         if (o1 instanceof Object[] && o2 instanceof Object[]) {
            return Arrays.equals((Object[]) o1, (Object[]) o2);
         }
         if (o1 instanceof boolean[] && o2 instanceof boolean[]) {
            return Arrays.equals((boolean[]) o1, (boolean[]) o2);
         }
         if (o1 instanceof byte[] && o2 instanceof byte[]) {
            return Arrays.equals((byte[]) o1, (byte[]) o2);
         }
         if (o1 instanceof char[] && o2 instanceof char[]) {
            return Arrays.equals((char[]) o1, (char[]) o2);
         }
         if (o1 instanceof double[] && o2 instanceof double[]) {
            return Arrays.equals((double[]) o1, (double[]) o2);
         }
         if (o1 instanceof float[] && o2 instanceof float[]) {
            return Arrays.equals((float[]) o1, (float[]) o2);
         }
         if (o1 instanceof int[] && o2 instanceof int[]) {
            return Arrays.equals((int[]) o1, (int[]) o2);
         }
         if (o1 instanceof long[] && o2 instanceof long[]) {
            return Arrays.equals((long[]) o1, (long[]) o2);
         }
         if (o1 instanceof short[] && o2 instanceof short[]) {
            return Arrays.equals((short[]) o1, (short[]) o2);
         }
      }
      return false;
   }

   /**
    * Return as hash code for the given object; typically the value of
    * <code>{@link Object#hashCode()}</code>. If the object is an array,
    * this method will delegate to any of the <code>nullSafeHashCode</code>
    * methods for arrays in this class. If the object is <code>null</code>,
    * this method returns 0.
    * @see #nullSafeHashCode(Object[])
    * @see #nullSafeHashCode(boolean[])
    * @see #nullSafeHashCode(byte[])
    * @see #nullSafeHashCode(char[])
    * @see #nullSafeHashCode(double[])
    * @see #nullSafeHashCode(float[])
    * @see #nullSafeHashCode(int[])
    * @see #nullSafeHashCode(long[])
    * @see #nullSafeHashCode(short[])
    */
   public static int nullSafeHashCode(Object obj) {
      if (obj == null) {
         return 0;
      }
      if (obj.getClass().isArray()) {
         if (obj instanceof Object[]) {
            return nullSafeHashCode((Object[]) obj);
         }
         if (obj instanceof boolean[]) {
            return nullSafeHashCode((boolean[]) obj);
         }
         if (obj instanceof byte[]) {
            return nullSafeHashCode((byte[]) obj);
         }
         if (obj instanceof char[]) {
            return nullSafeHashCode((char[]) obj);
         }
         if (obj instanceof double[]) {
            return nullSafeHashCode((double[]) obj);
         }
         if (obj instanceof float[]) {
            return nullSafeHashCode((float[]) obj);
         }
         if (obj instanceof int[]) {
            return nullSafeHashCode((int[]) obj);
         }
         if (obj instanceof long[]) {
            return nullSafeHashCode((long[]) obj);
         }
         if (obj instanceof short[]) {
            return nullSafeHashCode((short[]) obj);
         }
      }
      return obj.hashCode();
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(Object[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + nullSafeHashCode(array[i]);
      }
      return hash;
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(boolean[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + hashCode(array[i]);
      }
      return hash;
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(byte[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + array[i];
      }
      return hash;
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(char[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + array[i];
      }
      return hash;
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(double[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + hashCode(array[i]);
      }
      return hash;
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(float[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + hashCode(array[i]);
      }
      return hash;
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(int[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + array[i];
      }
      return hash;
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(long[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + hashCode(array[i]);
      }
      return hash;
   }

   /**
    * Return a hash code based on the contents of the specified array.
    * If <code>array</code> is <code>null</code>, this method returns 0.
    */
   public static int nullSafeHashCode(short[] array) {
      if (array == null) {
         return 0;
      }
      int hash = INITIAL_HASH;
      int arraySize = array.length;
      for (int i = 0; i < arraySize; i++) {
         hash = MULTIPLIER * hash + array[i];
      }
      return hash;
   }

   /**
    * Return the same value as <code>{@link Boolean#hashCode()}</code>.
    * @see Boolean#hashCode()
    */
   public static int hashCode(boolean bool) {
      return bool ? 1231 : 1237;
   }

   /**
    * Return the same value as <code>{@link Double#hashCode()}</code>.
    * @see Double#hashCode()
    */
   public static int hashCode(double dbl) {
      long bits = Double.doubleToLongBits(dbl);
      return hashCode(bits);
   }

   /**
    * Return the same value as <code>{@link Float#hashCode()}</code>.
    * @see Float#hashCode()
    */
   public static int hashCode(float flt) {
      return Float.floatToIntBits(flt);
   }

   /**
    * Return the same value as <code>{@link Long#hashCode()}</code>.
    * @see Long#hashCode()
    */
   public static int hashCode(long lng) {
      return (int) (lng ^ (lng >>> 32));
   }


   //---------------------------------------------------------------------
   // Convenience methods for toString output
   //---------------------------------------------------------------------

   /**
    * Return a String representation of an object's overall identity.
    * @param obj the object (may be <code>null</code>)
    * @return the object's identity as String representation,
    * or an empty String if the object was <code>null</code>
    */
   public static String identityToString(Object obj) {
      if (obj == null) {
         return EMPTY_STRING;
      }
      return obj.getClass().getName() + "@" + getIdentityHexString(obj);
   }

   /**
    * Return a hex String form of an object's identity hash code.
    * @param obj the object
    * @return the object's identity code in hex notation
    */
   public static String getIdentityHexString(Object obj) {
      return Integer.toHexString(System.identityHashCode(obj));
   }

   /**
    * Return a content-based String representation if <code>obj</code> is
    * not <code>null</code>; otherwise returns an empty String.
    * <p>Differs from {@link #nullSafeToString(Object)} in that it returns
    * an empty String rather than "null" for a <code>null</code> value.
    * @param obj the object to build a display String for
    * @return a display String representation of <code>obj</code>
    * @see #nullSafeToString(Object)
    */
   public static String getDisplayString(Object obj) {
      if (obj == null) {
         return EMPTY_STRING;
      }
      return nullSafeToString(obj);
   }

   /**
    * Determine the class name for the given object.
    * <p>Returns <code>"null"</code> if <code>obj</code> is <code>null</code>.
    * @param obj the object to introspect (may be <code>null</code>)
    * @return the corresponding class name
    */
   public static String nullSafeClassName(Object obj) {
      return (obj != null ? obj.getClass().getName() : NULL_STRING);
   }

   /**
    * Return a String representation of the specified Object.
    * <p>Builds a String representation of the contents in case of an array.
    * Returns <code>"null"</code> if <code>obj</code> is <code>null</code>.
    * @param obj the object to build a String representation for
    * @return a String representation of <code>obj</code>
    */
   public static String nullSafeToString(Object obj) {
      if (obj == null) {
         return NULL_STRING;
      }
      if (obj instanceof String) {
         return (String) obj;
      }
      if (obj instanceof Object[]) {
         return nullSafeToString((Object[]) obj);
      }
      if (obj instanceof boolean[]) {
         return nullSafeToString((boolean[]) obj);
      }
      if (obj instanceof byte[]) {
         return nullSafeToString((byte[]) obj);
      }
      if (obj instanceof char[]) {
         return nullSafeToString((char[]) obj);
      }
      if (obj instanceof double[]) {
         return nullSafeToString((double[]) obj);
      }
      if (obj instanceof float[]) {
         return nullSafeToString((float[]) obj);
      }
      if (obj instanceof int[]) {
         return nullSafeToString((int[]) obj);
      }
      if (obj instanceof long[]) {
         return nullSafeToString((long[]) obj);
      }
      if (obj instanceof short[]) {
         return nullSafeToString((short[]) obj);
      }
      String str = obj.toString();
      return (str != null ? str : EMPTY_STRING);
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(Object[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }
         sb.append(String.valueOf(array[i]));
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(boolean[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }

         sb.append(array[i]);
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(byte[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }
         sb.append(array[i]);
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(char[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }
         sb.append("'").append(array[i]).append("'");
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(double[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }

         sb.append(array[i]);
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(float[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }

         sb.append(array[i]);
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(int[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }
         sb.append(array[i]);
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(long[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }
         sb.append(array[i]);
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

   /**
    * Return a String representation of the contents of the specified array.
    * <p>The String representation consists of a list of the array's elements,
    * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are separated
    * by the characters <code>", "</code> (a comma followed by a space). Returns
    * <code>"null"</code> if <code>array</code> is <code>null</code>.
    * @param array the array to build a String representation for
    * @return a String representation of <code>array</code>
    */
   public static String nullSafeToString(short[] array) {
      if (array == null) {
         return NULL_STRING;
      }
      int length = array.length;
      if (length == 0) {
         return EMPTY_ARRAY;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < length; i++) {
         if (i == 0) {
            sb.append(ARRAY_START);
         }
         else {
            sb.append(ARRAY_ELEMENT_SEPARATOR);
         }
         sb.append(array[i]);
      }
      sb.append(ARRAY_END);
      return sb.toString();
   }

}
